1. Field of the Invention
The present invention relates to a circuit device.
2. Description of the Related Art
In recent years, portable electronics equipment such as a cell-phone, PDA, DVC, and DSC has become sophisticated at a rapid pace. In order for products of such equipment to be accepted in the marketplace, reduction in size and weight of the product is necessary. To satisfy the demands, a highly integrated system LSI is required. Moreover, ease of use and convenience are also required for the above electronics equipment. Thus, an LSI used in the above electronics equipment has to be more sophisticated and have higher performance. Therefore, the number of inputs and outputs are increased with increase of an integration degree in an LSI chip, whereas reduction of a size of a package is strongly demanded. In order to achieve a good balance between the above demands, development of a semiconductor package suitable for high-density mounting of semiconductor parts onto a substrate is strongly required. Various types of a packaging technique called as CSP (Chip Size Package) have been developed in order to deal with the above request.
There are various types of CSP. An exemplary type is described in Japanese Patent Laid-Open Publication No. 2000-243729. FIG. 5 is a cross-sectional view showing an exemplary semiconductor device described in Japanese Patent Laid-Open Publication No. 2000-243729.
A number of solder balls 72 as terminals for external connection are two-dimensionally arranged on a mounting-face side (upper side in FIG. 5) of a packaged semiconductor device 70. Each solder ball 72 is electrically connected to a corresponding electrode pad 76 of a semiconductor chip 71 through a Cu bump 74 and a Cu wiring 75 that are covered with a package resin 73. A peripheral portion 77 of the semiconductor chip 71 on the mounting-face side is diagonally cut, and part of-the package resin 73 also covers the peripheral portion 77. This wrap-around of the package resin 73 can improve reliability for sealing the semiconductor chip 71.
FIG. 6 is a cross-sectional view of a circuit device 70a in which the conventional semiconductor device 70 described above is mounted on a circuit board 78. The semiconductor device 70 is mounted on the circuit board (printed wiring board) 78 via the respective solder balls 72, thereby forming the circuit device 70a. A sealing resin 79 is provided between the semiconductor device 70 and the circuit board 78, so that the semiconductor device 70 is fixed on the circuit board 78. However, separation may occur at an interface between the package resin 73 and the semiconductor chip 71 because of a difference between a coefficient of linear expansion of the semiconductor chip 71 and that of the package resin 73 and the like, although the peripheral portion 77 of the semiconductor chip 71 on the mounting-face side in the circuit device 70a (semiconductor device 70) is diagonally cut so as to increase a contact area between the semiconductor chip 71 and the package resin 73 and improve joint strength therebetween. Especially, when a solder ball 72 having a large area is formed, stress load becomes large and it is going to be more likely that the separation occurs. Thus, it is necessary to provide the sealing resin 79 up to a sidewall of the semiconductor chip 71, so that the semiconductor chip 71 is fixed with the sealing resin 79.